1. Field
The present disclosure relates generally to hearing assistance devices such as, for example, implantable cochlear stimulation (“ICS”) systems.
2. Description of the Related Art
ICS systems are used to help the profoundly deaf perceive a sensation of sound by directly exciting the intact auditory nerve with controlled impulses of electrical current. Ambient sound pressure waves are picked up by an externally worn microphone and converted to electrical signals. The electrical signals, in turn, are processed by sound processor circuitry, converted to a pulse sequence having varying pulse widths and/or amplitudes, and transmitted to an implanted receiver circuit of the ICS system. The implanted receiver circuit is connected to an implantable electrode array that has been inserted into the cochlea of the inner ear, and electrical stimulation current is applied to varying electrode combinations to create a perception of sound. A representative ICS system is disclosed in U.S. Pat. No. 5,824,022, which is entitled “Cochlear Stimulation System Employing Behind-The-Ear Sound processor With Remote Control” and incorporated herein by reference in its entirety.
As alluded to above, some ICS systems include an implantable device, a sound processor, with the sound processor circuitry, and a microphone that is in communication with the sound processor circuitry. The implantable device communicates with the sound processor and, to that end, some ICS systems include a headpiece that is in communication with both the sound processor and the implantable device. The microphone may be part of the sound processor or the headpiece. In one type of ICS system, the sound processor is worn behind the ear (a “BTE sound processor”), while other types of ICS systems have a body worn sound processor unit (or “body worn sound processor”). The body worn sound processor, which is larger and heavier than a BTE sound processor, is typically worn on the user's belt or carried in the user's pocket. Body worn sound processor may also be held in a user's hand or placed on a surface such as a table at which the user is sitting. As used herein, a “body worn” sound processor is not a BTE sound processor. Examples of commercially available body worn sound processors include, but are not limited to, the Advanced Bionics Platinum Series™ body worn sound processor and the Advanced Bionics Neptune™ body worn sound processor.
One issue associated with ICS systems is ambient noise, i.e., speech or other sound from non-target sound sources (“non-target sources”), and it is desirable to suppress noise while preserving sound from the target sound source (“target source”). Beamforming is a known directional microphone technique that involves two or more microphones and can be used to preserve sound from the target source while filtering out or otherwise attenuating sound from non-target sources. BTE-based cochlear implant systems with beamforming microphone capabilities have been proposed in, for example, commonly assigned U.S. Pat. No. 7,995,771, which is incorporated herein by reference. The present inventors have determined that there are certain situations where BTE-based beamforming may be less than optimal. For example, in those instances where the user, either frequently or infrequently, turns his/her head to look at persons or objects other than the target source, a separate stationary microphone may be required. The present inventors have, therefore, determined that it would be advantageous to provide a body worn sound processor with directional microphone (e.g., beamforming) capabilities.